Wnt proteins signal through either the canonical Wnt/beta-catenin or the noncanonical Wnt/Ca2+ pathway. In some vertebrates, these pathways have been shown to function antagonistically. The beta-catenin pathway has been implicated in the maintenance and renewal of a variety of stem cells, including human embryonic stem cells (HESCs). The role of the Wnt/Ca2+ pathway in HESCs is unknown. The goal of this research is to determine the role of Wnt/Ca2+ signaling in the self-renewal and differentiation of HESCs. Stem cells (H7 or WA07 and HSF-6 or UC06) will be treated with either canonical or noncanonical purified Wnts or Wnt conditioned media. HESCs will also be transduced with lentivirus that express inducible conditional alleles capable of beta-catenin or Ca2+ directed signaling. Stem cells will be identified by staining for specific markers; also, their ability to differentiate into tissue derived from all three germ layers will be assessed by quantitative RT-PCR of specific tissue markers and by the ability to form teratomas upon injection into NOD/SCID mice. This research will enhance our understanding of the requirements for stem cell propagation, which, in turn, may contribute to the treatment of such diseases as diabetes and hemophilia.